"Green Feather Algae (Caulerpa sertularioides)" by bob in swamp is licensed under CC BY 2.0
Definition of Chlorophyta (Green Algae)
Green algae ( green algae ) are named based on the chloroplast are colored green. This green color exists because the dominant pigments are chlorophyll a and chlorophyll b , in addition to other types of pigments, namely carotene and xanthophyll. The shape of the chloroplast in green algae varies, some are bowl-like (for example in Chlamidomonas ), spiral (for example in Spirogyra ), and shaped like stars.
Although green algae are called algae, they are structurally and biochemically closer to plants. Today even many botanists (plant experts) who include it in the group of plants. Like plants, green algae store carbohydrates in the form of starch grains in their chloroplasts. The cell walls of some species of Chlorophyta are made up of cellulose, pectin, and other polysaccharides, such as plant cell walls.
Green algae are plankton that live floating in fresh water or sea. In addition to fresh water or sea, green algae also have a habitat in wet soils and some in dry places. Because it has chlorophyll, these algae can carry out photosynthesis and are autotrophs (can make their own food).
With the help of sunlight, Chlorophyta can carry out photosynthesis. Plankton is the main food source for animals that live in water. Plankton are referred to as producers. How do you know if Chlorophyta is doing photosynthesis?
Observe and pay attention to freshwater fish ponds during the day. If you pay close attention, algae exposed to sunlight will release gas in the form of small bubbles that stick to the edges of the pool, the gas is oxygen. Oxygen is a gas produced in the process of photosynthesis.
Chlorophyta or green algae consist of ± 7,000 species that live in waters and on land. Some green algae live in seawater, but most live in fresh water. There are green algae that live solitary and some are colonies. Unicellular green algae can move freely because they have flagella. Some types of green algae that colonize have attachments to the substrate that help them to stick firmly to the rocks at the bottom of the water.
Characteristics of Chlorophyta (Green Algae)
Green algae (Chlorophyta) have the following characteristics or general characteristics.
The body contains chlorophyll and is green in color. Cells contain chloroplasts which contain chlorophyll a, chlorophyll b, carotene and xanthophylls.
■ Core are eukaryotic cells because the cell nucleus already had membranes.
■ Has had a cell wall composed of cellulose.
■ Life floated in fresh water or sea water and acts as plankton as a food source of aquatic organisms.
■ There are unicellular (single-celled) and some are multicellular (multicellular) simple.
■ Characteristically autotorof, because chlorophyll to perform photosynthesis.
■ There is a solitary life (his own), colonize (groups) and there is also a form of symbiosis with other organisms. One example of a well-known mutualism symbiosis is the symbiosis between Chlorophyta and Fungi (fungi) forming Lichenes (lichens).
■ Body shape varies, some round, shaped filamentous (thread form), there is nothing like the sheets and higher plants.
■ The shape of chloroplasts assortment, there is nothing like Mangkung, spiral, star, mesh, and some are like sponges.
■ Have pirenoid as a storage area of photosynthesis in the form of starch and fat.
■ In addition to chloroplasts, the organelles that owned Chlorophyta include the Golgi apparatus, mitochondria and endoplasmic reticulum (ER).
■ Have a stigma (red eye spots) for green algae are motile (moving). This stigma serves to guide the algae towards light so that photosynthesis can occur.
■ Have one or two flagella are the same size for the length of motile green algae.
■ Have a contractile vacuole as osmoregulasi tool to regulate the osmotic pressure.
■ Having a permanent body shape.
■ Have habitats in freshwater, marine, wet soils, but some are in a dry place. 90% of Chlorophyta live in fresh water and 10% live in the sea as plankton or benthos, in the soil and attached to other organisms.
Classification of Chlorophyta (Green Algae)
Based on the shape and whether or not they can move, green algae are divided into 6 genera, namely:
■ Algae / celled green algae is not moving
Example:
1) Chlorella sp. spherical in shape, live in fresh water or sea water, reproduce vegetatively by dividing, widely used to study photosynthesis.
2) Cholococcum sp. spherical in shape, live in fresh water, reproduce vegetatively by forming zoospores generatively with isogamy.
■ Algae / celled green algae can move
Example:
1) Chlamydomonas sp. ovoid, has two flagella, chloroplasts are cup-shaped or ribbon-shaped containing pyrenoids and stigma. Reproduction by division and conjugation
2) Euglena viridis , shaped like an eye, has a flagellum, chlorophyll and sigma. Reproduction by dividing. Euglena there also group it into Protozoa .
■ algae / green algae form colonies do not move
Example: Hydrodictyon sp. , the colonies are net-shaped, mostly found in fresh water, reproduce vegetatively by fragmentation and generatively by conjugation.
■ algae / green algae shaped colonies that move
Example: Volvox globator , the shape of the colony resembles a ball composed of thousands of volvox which are connected to each other by cytoplasmic threads. Volvox is also grouped into Protozoa.
■ algae / green algae form filaments (yarn)
Example:
1) Spirogyra sp. (unbranched thread, single nucleus, spirally arranged ribbon-shaped chloroplast, many pyrenoids).
2) Oedogonium sp. (unbranched filaments, mesh-shaped chloroplasts, many pyrenoids, one large nucleus).
■ Algae / thalus shaped green algae (sheet)
Example:
1) Ulva lactua (sea lettuce), the shape of a sheet like a leaf and lives in the sea attached to a rock, can be eaten. Reproduction vegetatively by forming zoospores and sexually by isogamy.
1) Chara sp. , shaped like a tall plant, has stems and branches that are segmented, live in fresh water. Reproduction vegetatively by fragmentation and generatively by the meeting of egg cells produced by the oogonia and sperm cells produced by the antheridium.
How to Reproduction Chlorophyta (Green Algae)
This green algae can reproduce asexually (vegetatively) and also sexually (generatively).
Reproduction Asexually (Vegetatively)
■ Establishment of zoospores (spores wanderer). These spores have 4 hairs, contractile vacuoles, most have 1 eye spot (stigma), and can move by swimming because they have flagella.
■ binary fission. Green algae that reproduce by binary fission, usually carried out by single-celled algae (unicellular).
■ Fragmentation. Green algae that reproduce by fragmentation by thread-shaped algae or those in colonies.
Sexual Reproduction (Generative)
■ anisogamy. Recall what happened to Cyanophyta . In addition to asexually, green algae can also reproduce sexually (generatively), namely by anisogamy . The male gamete is always free-moving which closely resembles a zoospore, while the female gamete is sometimes immobile, so it is an oogonia. After mating, it will produce a zygote which will then grow into a new algae.
■ Conjugation. In addition, there are also green algae whose sexual reproduction takes place by conjugation, namely the fusion of two gametes to form a zygospore. This zygospore has no locomotion, so it cannot move.
Examples and Roles of Chlorophyta (Green Algae) in Life
Some examples of types of green algae include Chlamydomonas, Volvox, Protococcus, Spyrogyra, Ulothrix, Oedogonium, Chlorella, Chlorococcum, Ulva, and Chara. The following is an explanation of the characteristics, body structure and reproduction methods of several types of green algae and their benefits in life (if any).
Chlorococcum and Chlorella are single-celled Chlorophyta that cannot move and are microscopic. The chloroplasts are bowl-shaped, microscopic in size, and live as freshwater plankton. Chlorococcum and Chlorella can reproduce asexually by forming zoospores that move with two flagella. Chlorella can reproduce by cell division.
Chlorella can be used as a drug, even now being developed for drugs that are packaged in capsule form. Chlorella also gives great hope to overcome the need for alternative food ingredients in the future. Reproduction is very fast in a good environment, the ideal temperature for photosynthesis is around 25 o C.
The process in the Chlorella laboratory is used in photosynthesis research. In photosynthesis it produces carbohydrates, proteins and fats. Organic substances, carbon dioxide and minerals are applied to the substrate and the light intensity and duration of irradiation can be adjusted to produce the desired carbohydrates, fats and proteins.
Chlamydomonas is a single-celled Chlorophyta that can move and is microscopic. The cells are ovoid in shape. Chlamydomonas cells contain one nucleus, one vacuole, and chloroplasts. The locomotion consists of two flagella. Cup shaped chloroplasts. Eyespots and pyrenoids are located in the bowl which serves as a place for the formation of starch. Chlamydomonas can reproduce in two ways, namely by the formation of zoospores and conjugation.
Spirogyra and Oedogonium are cells that form threads or elongated strands like threads and are microscopic. Spirogyra and Oedogonium mostly live in fresh water. Spirogyra have cells containing chloroplasts in the form of spiral bands and in one cell containing one nucleus, can reproduce by fragmentation and conjugation.
Oedogonium has mesh-shaped chloroplasts and in one cell contains one nucleus and can reproduce by zoospores and the fusion of spermatozoa (antheridium) with ova (oogonia) produced by different threads. The result of the fusion is a zygote that can grow into a new individual.
Chara and Ulva are Chlorophyta in sheet form. Chara is an algae that lives in fresh water, has segments that contain nucules and globules. The nucleus contains the ovum-producing archegonia. The globules contain spermatozoid-producing antheridia. Fertilization of an ovum by a spermatozoon will produce a zygospore which will then develop into a new individual. Asexual reproduction is done by fragmentation.
The ulva has a thallus in the form of a sheet consisting of two layers of cells. The shape of the Ulva thallus is like a lettuce leaf, the chloroplast is cup-shaped. Ulva can live in brackish water, salt water, or attached to wood and rocks along the coast. Ulva reproduces asexually with zoospores with fla agella and will form haploid Ulva. Sexual reproduction is characterized by the union of male and female sex cells to form a zygote. The zygote will develop into a diploid Ulva.
Hydrodictyon is a Chlorophyta in the form of immobile colonies. It is found in fresh water and forms a net-like colony. Reproduce asexually by spores and fragmentation, while sexually by conjugation.
Volvox is a Chlorophyta that is in the form of colonies and moves. Volvox live in fresh water and each cell has two flagella and stigma, a spherical colony with a cell number of 500 – 50,000 cells . Asexual reproduction is done by fragmentation, while sexually by conjugation.
